This invention relates to a class of metal complexes containing a substituted indenyl ligand, and to polymerization catalysts derived from such complexes that are particularly suitable for use in a polymerization process for preparing homopolymers and copolymers of olefins or diolefins, including copolymers comprising two or more olefins or diolefins such as copolymers comprising an α-olefin and ethylene or a monovinyl aromatic monomer and ethylene.
Constrained geometry metal complexes and methods for their preparation are disclosed in U.S. Pat. No. 5,703,187. This publication also teaches the preparation of certain novel copolymers of ethylene and a hindered vinyl monomer, including monovinyl aromatic monomers, having a pseudo-random incorporation of the hindered vinyl monomer therein. Additional teachings of constrained geometry catalysts may be found in U.S. Pat. Nos. 5,321,106, 5,721,185, 5,374,696, 5,470,993, 5,541,349, and 5,486,632, as well as WO97/15583, and WO97/19463.
Metal complexes containing a substituted indenyl group substituted in 2 or 3 position with a substituent were previously disclosed in U.S. Pat. Nos. 6,015,868 and 5,866,704. Similar metal complexes containing heteroatom substituents were disclosed in WO98/06728, published Feb. 19, 1998. Certain highly active, polycyclic aromatic, metal complexes, especially derivatives of s-indacenyl or cyclopentaphenanthrenyl ligand groups are disclosed in U.S. Pat. Nos. 6,034,022 and 6,329,486.
Despite the advance in the art obtained by the foregoing metal complexes, catalysts possessing improved catalytic performance are still desired by the industry. In particular, it would be desirable to provide improved metal complexes that may be readily synthesized and possess improved catalyst performance.